Screw-tapping machine



J. G. BAKER.` SoreW'Tappfing Machine.

No. 232,918. A Patented oct. 5,1880.

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JOHN G. BAKER, OF PHILADELPHIA, PA., ASSIGNOR TO THE ENTERPRISE MANUFACTURING COMPANY OF PENNSYLVANIA.

SCREW-TPFING MACE-HNE.

SPECIFICATION forming part of Letters Patent No. 232,918, dated October 5, 1880.

Application filed December 7, 1878.

To all whom it may concern Be itknown that I, JOHN G. BAKER, ofPhiladelphia, Pennsylvania, have invented a new and useful Improvement in Tapping-Machines,

of which the following is a specification.

The object of my invention is to rapidly and accurately tap holes in metal by the automatic mechanism described hereinafter.

In the accompanying drawings, Figure l is 1o a side view of my improved tapping-machine, partly in section. Fig. 2, a front view; Figs. 3, 4., 5, 6, and 7, views representing detached portions of the machine, drawn to an enlarged scale 5 and Figs. 8, 9, and 10, detached views i5 of parts of the machine, drawn to the same scale as Figs. l and 2.

A is the frame of the machine, and B the table on which the objects to be tapped are placed and temporarily secured. This table 2o being adapted to vertical guides on the frame, and admitting of being raised or lowered by means of a screw, C, adapted to a fixed nut, a, and geared by bevel-wheels to a horizontal shaft, D, provided with a suitable handle. As

this mechanism for the vertical adjustment oi' the table has no connection with the operating devices ofthe machine, and as other adjusting appliances may be used in connection with the table, a more minute description of the said 3o mechanism will be unnecessary.

E is the tapping-spindle, carrying at its lower end the chuck b, for receiving and retaining the tap W, and connected at the upper end to a lever, F, through the medium of a 3 5 swivel, c, in which the spindle can turn freely.

The tapping spindle has its lower bearin g in the projection d of the trame, and its Lipper bearing in the hub e of a wheel, Gr, Fig. 4, the said hub having its bearin g in the projection 4o d of the frame.

The spindle passes through a hollow cylinder or driver, H, situated between the two projections d d', ot' the frame, the driver having a bevel-wheel, j', gearing into a pinion,

4 5 f', on the horizontal shaft I, referred to hereinafter.

Motion is communicated from t-he driver to the tapping-spindle through the medium of a cross-head, J, which is secured to the spindle, and between which and the bottom of the 5o driver intervenes a spring, h. The opposite ends of the cross-head are adapted to vertical Vguiding-grooves in the driver, so that while the said driver must always drive the tappingspindle, the latter is free to move up and down. In order to avoid friction the opposite ends of the cross-head are furnished with anti-friction rollers adapted to the vertical grindinggrooves of thecylinder.

Within the cog-wheel G and the cap G', se- 6o cured to the same, is a circular chamber, K, straight in the middle, but having :a tapering contraction at top and bottom, and on the spindle E is a loose friction-clutch, if, adapted to the contracted upper end of the chamber, a similar friction-clutch, k', loose on the spindle, being adapted to the contracted lower end of the chamber, and the lower clutch being loosely confined to the upper clutch by collars on the spindle. 7o

The clutches are recessed so as to contain a ratchet-pinion, Z, Fig. 7, which is secured to the spindle, and in a recess in the edge of each clutch is a small spring pawl, m, adapted to the teeth of the intervening wheel l., the pawls 7 5 of the two clutches bearing the relation shown in Fig. 7 to each other.

We will suppose that any object confined to the table B has an oritce to be threaded, that the spindle and the cylinder or driver H is 8o revolving in the direct-ion of the arrow, and that the tap is introduced into the hole by so manipulating the lever F as to depress the spindle. As soon as the teeth of the tap bite inthesidcsot` the holethelevermaybereleased, for the tendency ofthe tap, as it is being turned, and now that it is beginning to form a thread in the hole, is to draw the spindle downward and to compress the spring intervening between the cross-head J and bottom of the driver 9'0 H. Then the tapping has been continued far enough into or through the hole in the object on the table the clutch k will have reached the lower contracted end of the chamber K, Fig. 4, and willbe in such frictional contact therewith that the pinion l, acting against the Q essere pawl m of the clutch, will move the wheel G far enough round to effect the reversal of the spindle through the medium of the inechanism explained hereinafter. When the movement of the spindle is reversed the tap will be unscrewed from the orifice and the spindle will gradually rise, the spring h, before referred to, aiding the tap to elevate the spindle, which carries with it the two clutches k 7c' and intervening ratchet-pinion l. When the clutch 7c' comes in contact with the contracted upper end of the chamber K the pinion l, acting on the pawl of the said clutch k, will, through the latter, turn the wheel G to an extent sufficient to cause a reversal of the motion of the spindle through the medium of the devices described hereinafter; and another hole in the object on the table, or in another object afxed thereto, can be tapped after iirst depressing the spindle by the lever F, and thereby introducing the tap into the hole, after which a repetition of the above-described operations takes place.

The drivin g-sl1aft I, which has been referred to above, has its bearings iu the frame of the machine, and on this shaft are two loose pulleys, L L', one for receiving a straight belt and the other for receiving a cross-belt7 so that the two pulleys will always revolve in contrary directions.

On the shaft I, between the two pulleys, is a sleeve, M, capable of sliding on, but revolving with,the shaft, and this sleeve has two conical friction-clutches, N N',one adapted to a conical bearing in the pulley L, and the other to a similar bearing in the pulley L'.

P is a horizontal bar, arranged to slide in the frame of the machine, and to this bar is secured an arm, a, the upper forked end of which has projections or anti-friction rollers adapted to a groove in the sleeve M.

On the bar P is arranged a sliding rack, P', to which is geared a pinion, Q, on the vertical shaft Q', which is geared, by any suitable system of intervening wheels, to the wheel G, the hub of which, as before remarked, has its bearing in the projection d of the frame, and is independent in its movement of the tappingspindle.

On the vertical shaft Q', below the pinion Q, is a cam, R, adjoining one arm of a triggerlever, S, which is pivoted to a vertical stud, t, fixed to the frame of the machine, the other arm of thelever having a projection, u, adapted to either of two notches in a collar, t, in the sliding bar P, a suitable spring, Q tending to maintain the projection in one or other of the notches .fr w' in the said collar. In the present instance, and as shown in Fig. 8, the pro- 6o jection a is in the notch x, and the clutch N' is in frictional contact with the pulley L' in which case the tapping-spindle will turn in the direction of the arrow, and the tap will be in the act of threading the hole in the object on the table B.

When the spindleE reaches the limit of its upward movement the wheel G will be turned to alimited extent, for the reasons above given, and the pinion Q will also be turned, thereby moving the slide P in the direction of the arrow, and compressing the spring q', one end of which is secured to the bar P, the other end being acted on by the lugp' of the slide P'. On the further movement of the vertical shaft Q', its cam It, acting on the lever S, will withdraw the projection a of the lever from the notch m, when the bar will be at liberty to be acted on by the compressed spring g, which will so move the bar that its arm n will throw the clutch N into gear with the wheel L, and the lever S, becoming free from the control of the cam, its projection u will enter the notch 00', and the clutch N will continue to remain in gear with Ithe pulley L until a reverse movement of the pinion Q takes place, when the spring q will be compressed, the bar P will be again released from the control of the lever, and the clutch N' will be moved into gear with the pulley L'.

Each of the clutches N N' is made in two parts, a' and a", as best observed in Fig. 3, the central part, n', forming part of the sleeve M, and the outer part, a", which has the conical bearing-surface, being arranged to slide on but turning with, the part a'. Intervening springs w tend to force the part a", which has the friction-surface, away from the part n', to an extent limited by a nut or collar, w.

If the friction-clutches were made solid, as usual, and there should be any play or inaccuracy of fitting of the proj ectiona of the trigger-lever in the notches of the collar on the shifting-bar P, the hearing of one or both of the clutches against the pulleys might not be assured; but under the same circumstances the bearing of the improved clutch would be assured, owing' to the action of the springs fw on the portion a" of the clutch, which will bear with its friction-surface against that of the pulley in spite of any imperfection in the driver for retaining the shiftingbar.

I claim as my invention- 1. The combination of the tapping-spindle, its cross-heads and the driver H with the spring It.

2. The combination of the tapping-spindle, the friction-clutches k k', each having springpawls, and the ratchet-wheel l, all carried by the said spindle, with the' reversing-wheel G, having a chamber with contracted ends adapted to the said clutches, all substantially as set forth.

3. The combination of the driving-shaft, the two pulleys L L', and the two clutches N N', adapted to the pulleys and connected together by a sleeve, M, with the tapping-spindle E, and with devices by which the said tappingspindle is caused to operate the clutches at the limits of its upward and downward movements, as specified.

IOO

IIO

4. The combination of thel tapping-spindle In testimony whereof I have signed myname E, and reversing-Wheel G, the clutches N N', to this specification in the presence of two 1o f the vshifting-har P, springs for actuating the subscribing Witnesses. bar, and a trigger for retaining and releasing 5 the same, with mechanism through the me- JOHN G' BAKER' dum ot' which the said reversing-wheel G is Witnesses: caused to compress the springs and aotuate ALEX. PATTERSON,

the trigger, all substantially as described. HARRY SMITH. 

